CN1221719A

CN1221719A - Prodn. tech. of disposable multi-element compound fertilizer

Info

Publication number: CN1221719A
Application number: CN 98114356
Authority: CN
Inventors: 王可义
Original assignee: CANG ANZHI
Current assignee: CANG ANZHI
Priority date: 1998-09-25
Filing date: 1998-09-25
Publication date: 1999-07-07
Anticipated expiration: 2018-09-25
Also published as: CN1088446C

Abstract

A one-pass applied multi-elemtn compound fertilizer is prepared from bentone, heavy calcium, potassium chloride and urea through granulating based on the heat from reaction between sulfuric acid and liquefied nitrogen, drying and cooling to obtain compound NPK fertilizer. It features less liquid phases and low viscosity during its preparing process (resulting in easy breaking and granulating), and modification of heavy calcium to reduce crystallized water for higher physical nature.

Description

Production process of disposable multi-element compound fertilizer

The invention relates to a production process of a chlorine-based nitrogen-phosphorus-potassium compound fertilizer, in particular to a production process of a disposable multi-element compound fertilizer which is prepared by taking a phosphorus source, a potassium source, urea and an additive as raw materials.

In the prior art, when the chlorine-based nitrogen-phosphorus-potassium compound fertilizer is produced, free phosphoric acid and monocalcium phosphate contained in the coarse whiting can react with urea to generate urea phosphate and a mixture of monocalcium phosphate and urea, and original crystal water of monocalcium phosphate can be released. The two substances have high solubility and can be dissolved in the water contained in the heavy calcium to increase the liquid phase of the mixture, so that the material becomes sticky and is not beneficial to crushing and granulating, therefore, when the urea-heavy calcium is used for producing the compound fertilizer, theheavy calcium is modified.

The invention aims to provide a production process of a disposable multi-element compound fertilizer, which makes monocalcium phosphate in heavy calcium react with liquid nitrogen to convert dicalcium phosphate and monoammonium phosphate so as to change the physical properties of raw materials and reduce the release of crystal water.

In order to achieve the purpose, the invention adopts the following technical scheme: the invention is a nitrogen-phosphorus-potassium compound fertilizer which is produced by granulating, drying and cooling an additive (bentonite), a phosphorus source (triple superphosphate), a potassium source (potassium chloride) and urea according to a certain proportion on the basis of taking sulfuric acid and liquid ammonia as reaction heat, and is characterized in that:

(1) according to the ratio of bentonite to heavy calcium (P)₂O₅= 41%: potassium chloride (K)₂O =62 percent and urea(= 64%) = 1: 6.43: 2.87: 8.7 (weight ratio) and uniformly mixing;

(2) modifying the coarse whiting by adopting an amino-transfer method, introducing liquid ammonia (containing 82.3 percent of nitrogen) at a raw material inlet of a granulator, adding the liquid ammonia according to 1.35 percent of the amount of a finished product, and carrying out ammoniation treatment on the coarse whiting in the raw material;

(3) heating the materials in the granulating bed layer by adopting ammonia-acid reaction heat, and adding liquid ammonia and sulfuric acid into the granulating section at the same time according to the weight ratio of 1: 2-3.5;

(4) in the reaction process of the ammonia and the acid, the temperature of the material at the outlet of the granulator is ensured to be between 60 and 80 ℃, the PH value is between 5.5 and 7.0, and the water content is less than or equal to 3.0 percent;

(5) the material at the outlet of the granulator is sent into a dryer for drying, the temperature at the inlet of the dryer is between 110 and 165 ℃, and the temperature of the material at the inlet of the dryer is ensured to be between 60 and 70 ℃, and the moisture content is less than or equal to 2.0 percent;

(6) and (3) feeding the material at the outlet of the granulator into a cooling machine for cooling treatment, and ensuring that the temperature of the material is reduced to 35-55 ℃.

The main reaction equation is:

the invention has the positive effects that: the purpose of the sulfuric acid and the liquid ammonia which are put into the production process is that the reaction heat is utilized to heat the materials for granulation, the generated ammonium sulfate is mixed with the phosphoric acid-calcium and then mixed with the urea, the ammonium sulfate reacts with the monocalcium phosphate to generate ammonium gypsum double salt, and the generated ammonium phosphate avoids the degradation of the water-soluble phosphorus pentoxide, so that the mixedmaterials have good physical properties and are easy to granulate.

Example 1:

taking 46 kg of bentonite, 298 kg of heavy calcium, 133 kg of potassium chloride, 403 kg of urea, 47 kg of liquid ammonia and 105 kg of sulfuric acid, and producing the total nutrient (N + P) of the product according to the production process₂O₅+K₂O) is more than or equal to 42 percent, total nitrogen (N) is more than or equal to 22 percent, available phosphorus (P)₂O₅) Not less than 12%, the percentage of water-soluble phosphorus in phosphorus is not less than 50%, and potassium chloride (K)₂O) content is more than or equal to 8 percent, moisture (free water) is less than or equal to 2.2 percent, average compression strength N of the particles is more than or equal to 12 percent, and the particle size (1.0-4.75mm) is more than or equal to 85 percent.

Claims

1. The production process of the disposable multi-element compound fertilizer is characterized in that: the nitrogen-phosphorus-potassium compound fertilizer is produced by using bentonite, triple superphosphate, potassium chloride and urea in the weight ratio of 1 to 6.43 to 2.87 to 8.7, and through pelletizing, drying and cooling on the basis of using sulfuric acid and liquid ammonia as reaction heat.

2. The production process according to claim 1, characterized in that:

(1) evenly mixing bentonite, heavy calcium, potassium chloride and urea in a weight ratio of 1: 6.43: 2.87: 8.7;

(2) modifying the coarse whiting by adopting an amino-transfer method, introducing liquid ammonia (containing 82.3 percent of nitrogen) at araw material inlet of a granulator, adding the liquid ammonia according to 1.35 percent of the amount of a finished product, and carrying out ammoniation treatment on the coarse whiting in the raw material;